This invention relates to an arrangement for mixing fluids and for growing crystals according to the vapor diffusion method, particularly under conditions of weightlessness.
For crystal growth experiments, it has been found to be advantageous first to transport a protein solution and a precipitating agent separately, and to mix them at the site of crystallization. This applies also to the selective feeding of a seed crystal into an already mixed protein solution immediately before the start of the crystallization.
In the "hanging-drop" method of crystal growth, a drop with a starting volume V.sub.1 of an unsaturated solution is suspended and slowly evaporated to a smaller volume V.sub.2 so that a desired supersaturation of the dissolved substance occurs, which leads to the crystallization of this substance. This method can also be carried out under conditions of reduced gravity, in which larger drops and larger crystals can be produced.
In contrast to an earth borne application, however, an arrangement that is suitable for space must have the following characteristics:
Before the beginning of the experiment, the starting constituents must be stored in a tightly sealed manner. PA0 If possible, the mixing should take place without manual intervention. PA0 If possible, the drop should be produced without manual intervention. PA0 If possible, the feeding of the seed crystals should take place without manual intervention. PA0 After completion of the process, the fluid must again be stored in a tightly sealed manner, and must fill the storage vessel completely. Gas bubbles or similar phenomena must be avoided because otherwise the crystals may be destroyed during return to earth. So that a return can be ensured that is free of gas bubbles, the volume in which the crystallization product is returned is calculated in advance, and the container is dimensioned accordingly.
It is an object to the present invention to provide an arrangement for carrying out crystal growing experiments, particularly under conditions of weightlessness, by which the starting fluids can be transported separately and can be mixed at the desired point in time.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.